<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript" src="js/office.js"></script>
    <script type="text/javascript" src="js/jquery-1.7.2.js"></script>
</head>
<body>
    <button id="run">Start</button>
</body>
<script type="text/javascript">
    $("#run").click(() => tryCatch(run));

    async function run() {
        await Excel.run(async (context) => {
            const sheet = context.workbook.worksheets.getActiveWorksheet();

            console.log("Your code goes here");

            await context.sync();
        });
    }

    /** Default helper for invoking an action and handling errors. */
    async function tryCatch(callback) {
        try {
            await callback();
        } catch (error) {
            // Note: In a production add-in, you'd want to notify the user through your add-in's UI.
            console.error(error);
        }
    }
</script>
</html>